How can you 3D print faster, with a wide choice of materials, while maintaining good part quality? That’s what a team of researchers at Lawrence Livermore National Laboratory (LLNL) has set out to do. They have developed a new approach using microwave energy to harden the material. This 3D printing technique has been dubbed Microwave Volumetric Additive Manufacturing (MVAM) and could be compatible with more materials, especially opaque or filled resins. It would also enable the creation of large parts, although the team has only tested the design of smaller structures for the time being.
Developments in resin 3D printing are becoming increasingly important, and we’ve already covered many topics relating to volumetric additive manufacturing, which uses projected light to increase speed. Researchers at LLNL realized that this technique had certain limitations, including that it couldn’t use opaque or fiber-filled resins, which had to be transparent to let the light through. So, the team set out to remove this constraint and turned to the energy produced by a microwave.
The research team behind this project (photo credits: Blaise Douros/LLNL)
Indeed, the energy produced by a microwave is capable of penetrating deeper into the resin to harden it, thus broadening the spectrum of compatible materials. Saptarshi Mukherjee, a specialist in applied electromagnetism and one of the LLNL researchers, explains: “I think this is going to revolutionize the way people think about additive manufacturing. If we think of many applications – aerospace, automotive, nuclear industry – their geometries are simple, but they are large and require rapid prototyping. One of the main effects [of MVAM] is that if we can maintain a stock of materials surrounded by an array of microwave antennas, we can now consider creating large simple or complex geometries at scale using microwaves.”
In concrete terms, the team has developed a system capable of controlling microwave beams, the aim being to optimize power and curing time to provide better thermal control. Several tests were carried out to demonstrate the effectiveness of this technique. At 40 watts, the researchers were able to cure the resin in just 2.5 minutes. By increasing the power, they could achieve speeds of around 6 seconds! Using a wave calculation model, they explain that they can see how the energy propagates inside the resin and how this affects the curing stage. Co-investigator Johanna Schwartz adds, “We have a unique opportunity to broaden the definition of what is ‘printable’, accessing chemistries not previously possible in light-based systems.” It would then be possible to process opaque and composite resins and obtain parts with expanded properties.
For the time being, the 3D printing process developed by LLNL is still in its infancy and needs to overcome several barriers, not least the price of microwave energy. Saptarshi Mukherjee concludes: “High-power microwave devices are extremely expensive – a one-kilowatt pulsed microwave amplifier system can cost between $50,000 and $100,000. We’re looking at how we can design or build some of these circuits or hardware ourselves to dramatically reduce costs and show that the overall concept works before large projects or external sponsors are ready to invest in the technology.” While we await further developments, read the official press release HERE.
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*Cover photo credits: Blaise Douros/LLNL